Microhardness evaluation around composite restorations using fluoride-containing adhesive systems

Abstract

he purpose of this study was to evaluate the microhardness of dental enamel around composite restorations bonded with fluoride-containing adhesive systems (FCAS), after thermo-and pH-cycling protocols. Standardized cylindrical cavities were prepared on enamel surfaces of 175 dental fragments, which were randomly assigned into seven experimental groups (n=25). Four groups used FCAS: Optibond Solo (OS); Prime&Bond 2.1 (PB); Syntac Sprint (SS) and Tenure Quick (TC). Other groups consisted of "Sandwich" technique restoration (STR) (glass ionomer liner + hydrophobic adhesive resin /restorative composite) or used Single Bond with (SB) or without (SBWC) cycling protocols. Adhesive systems were applied according to manufacturers' instructions and cavities were restored with a microfilled composite (Durafill VS). After finishing and polishing, all groups were submitted to 1,000 thermal cycles (5 o C and 55 o C) and to demineralization (pH 4.3) and remineralization (pH 7.0) cycling protocols, except for SBWC group. The Knoop microhardness of enamel surfaces were measured around restorations. Indentations were recorded at 150, 300 and 450-mm from the cavity wall. Data were analyzed by two-way ANOVA and Duncan's Test (a=0.05%). Means ± SD of enamel microhardness for the groups were (Kg/mm b . SBWC group, which was not submitted to thermo-and pH-cycling protocols, showed the highest enamel microhardness mean value and the FCAS resulted in lower microhardness values. At 450 mm from the cavity wall, the enamel microhardness increased significantly. Uniterms: Dental enamel; Fluoride; Adhesive systems; Microhardness. objetivo deste estudo foi avaliar a microdureza do esmalte dental ao redor de restaurações em compósito que utilizaram sistemas adesivos contendo fluoretos (FCAS), após tratamento dessas superfícies restauradas aos protocolos de ciclagem térmica e pH. Cavidades cilíndricas padronizadas foram preparadas em 175 superfícies de esmalte de fragmentos dentais, os quais foram aleatoriamente divididos em sete grupos (n=25). Quatro grupos utilizaram os FCAS: Optibond Solo (OS); Prime&Bond 2.1 (PB); Syntac Sprint (SS) e Tenure Quick (TC). Outros grupos consistiram em restaurações "Sandwich" (STR -ionômero de vidro como base + restauração em composíto) ou utilizaram Single Bond com (SB) ou sem (SBWC) ciclagens. Os sistemas adesivos foram aplicados segundo as instruções dos fabricantes e as cavidades restauradas com compósito microparticulado (Durafill VS). Após o acabamento e polimento, todos grupos foram submetidos a 1.000 ciclos térmicos (5 o C e 55 o C) e a um protocolo de ciclagem de pH (desmineralização-pH 4,3 e remineralização-pH 7,0), exceto para o grupo SBWC. A microdureza das superfícies de esmalte foi mensurada ao redor das restaurações. Indentações foram feitas nas distâncias de 100, 300 and 450-mm da parede cavitária. Os dados foram analisados pela ANOVA (2 fatores) and Teste de Duncan (5%

Influence of photo-activation source on enamel demineralization around restorative materials

“…The first AL was cleared for marketing and clinical use in 1991 by the U.S. Food and Drug Administration (FDA). 21 Since that time, AL has been used clinically to light-activate dental materials 17 and has been shown to be capable of polymerizing compomers 2 or CR. 20,22 The use of AL in dentistry reduces the chair time in dental offices.…”

“…The dynamic pH-cycling model has been shown to be adequate for studies of enamel caries-like lesions. 6,18 Various protocols (e.g., with 5 pH cycles 17 or 14 days in demineralization solution 16 ) have been used to simulate demineralization/remineralization phenomena in the oral environment with different restorative materials 2 and activation sources. 16 Nevertheless, other important clinical variables that are not addressed in the in vitro setting should also be considered, such as the cariogenicity and frequency of the patient's diet or presence of saliva.…”

“…The induction of caries-like lesions around restorations in vitro is an experimental approach that provides information about the clinical behavior of the restorative materials under the experimental conditions. 6,17 The objective of this study was to evaluate the cariostatic potential of the light-activation source and restorative materials in vitro after a pH challenge. The response variable evaluated was the Knoop microhardness (KHN) profile of human enamel around and in the superficial area of the restorative materials.…”

Análise in vitro da resistência de união da resina composta contendo biomaterial S-PRG(Ionômero de Vidro com Superfície Pré-Ativada) à dentina erodida

“…Os dentes permaneceram armazenados em solução de cloramina T a 0,5% sob refrigeração (4 o C) por um período máximo de três meses após a data de extração (Armstrong, et al, 2017;Mobarak et al, 2010). Foi realizada a limpeza dos dentes com a utilização de curetas periodontais (Duflex, SS White, Rio de Janeiro, RJ, Brasil) e o polimento com pedra pomes (SS White, Rio de Janeiro, RJ, Brasil) e água com o auxílio de escovas tipo Robinson (KG Sorensen, Barueri, SP, Brasil) em baixa rotação, seguidas de lavagem com água destilada (Armstrong, et al,2017;Magalhães et al, 2005) Após a limpeza, os dentes foram fixados com cera pegajosa (Asfer Indústria Química Ltda, São Paulo, Brasil) em um placa de metal (Jig de Gibraltar), com a junção amelo-dentinária perpendicular à placa, para a remoção (sentido mésio-distal) do esmalte da região coronária e da porção radicular ( Figura 5.1(A)). Inicialmente, os dentes tiveram o esmalte oclusal removido com disco diamantado dupla face (Buehler, UK Ltd, Lake Bluff, IL, EUA), em cortadeira metalográfica para a exposição da superfície dentinária, em baixa rotação (100 rpm (Armstrong, et al, 2017).…”